Shawn (Sheng-Chieh) Chen, Ph.D.

Associate Professor, Department of Mechanical and Nuclear Engineering | VCU College of Engineering

Richmond, VA, UNITED STATES

Shawn's research interests include airborne and liquid-borne nanoparticle filtration, NanoEHS, and indoor and urban air pollution control.

Links (2)

Biography

Sheng-Chieh Chen received Environmental Engineering Ph.D. degree from the Institute of Environmental Engineering, National Chiao Tung University in 2006. During his study for PhD, he focused on various research topics including the sampling and analysis of nanoparticles in urban area, nanopowder manufacturing workplaces and many other ambient environments; 3-D numerical simulations of flow field and gas pollutant dispersion in a real cleanroom and particle transport in a critical orifice and axial flow cyclone; design and calibration of aerosol sampling and control device, e.g. axial nanoparticle cyclones, cascade impactors and the real-time aerosol instruments. He is now interested in the topics of airborne and liquid-borne nanoparticle control and environmental sustainability-related research.

Industry Expertise (3)

Education/Learning

Research

Nanotechnology

Areas of Expertise (5)

Nanofiltration and ultrafiltration

Air pollution control

Aerosol sampling and instrumentation

Indoor Air Quality

CFD simulation

Accomplishments (1)

MIC-PARTICUOLOGY Excellent Article Award (professional)

An award committee of the Chinese Society of Particuology chooses two most cited articles according to the calculated annual average SCI citation numbers for all articles during the same period.

Education (2)

National Chiao Tung University: Ph. D., Environmental Engineering 2006

Tam Kang University: B.S., Water Resources and Environmental Engineering 1999

Selected Articles (3)

PM2.5 in China: Measurements, sources, visibility and health effects, and mitigation

Particuology

Concern over the health effects of fine particles in the ambient environment led the U.S. Environmental Protection Agency to develop the first standard for PM2.5 (particulate matter less than 2.5 μm) in 1997. The Particle Technology Laboratory at the University of Minnesota has helped to establish the PM2.5 standard by developing many instruments and samplers to perform atmospheric measurements. In this paper, we review various aspects of PM2.5, including its measurement, source apportionment, visibility and health effects, and mitigation. We focus on PM2.5 studies in China and where appropriate, compare them with those obtained in the U.S. Based on accurate PM2.5 sampling, chemical analysis, and source apportionment models, the major PM2.5 sources in China have been identified to be coal combustion, motor vehicle emissions, and industrial sources. Atmospheric visibility has been found to correlate well with PM2.5 concentration. Sulfate, ammonium, and nitrate carried by PM2.5, commonly found in coal burning and vehicle emissions, are the dominant contributors to regional haze in China. Short-term exposure to PM2.5 is strongly associated with the increased risk of morbidity and mortality from cardiovascular and respiratory diseases in China. The strategy for PM2.5 mitigation must be based on reducing the pollutants from the two primary sources of coal-fired power plants and vehicle emissions. Although conventional Particulate Emission Control Devices (PECD) such as electrostatic precipitators in Chinese coal-fired power plants are generally effective for large particles, most of them may not have high collection efficiency of PM2.5. Baghouse filtration is gradually incorporated into the PECD to increase the PM2.5 collection efficiency. By adopting stringent vehicle emissions standard such as Euro 5 and 6, the emissions from vehicles can be gradually reduced over the years. An integrative approach, from collaboration among academia, government, and industries, can effectively manage and mitigate the PM2.5 pollution in China.

Liquid filtration of nanoparticles through track-etched membrane filters under unfavorable and different ionic strength conditions: Experiments and modeling

Journal of Membrane Science

Nanoparticle deposition experiments under unfavorable conditions were conducted experimentally and theoretically. The 0.2 and 0.4 µm rated track-etched membrane filters were challenged with 60, 100, 147, 220, 350 and 494 nm polystyrene latex (PSL) particles with different ionic strengths ranging from 0.005 to 0.05 M. The capillary tube model, with replacing the viscosity of air to water, was used to estimate the initial efficiency, or the transport efficiency of the particles to the filter surface, which was corrected in a second step by allowing the detachment of the nanoparticles according to the sum of adhesive and hydrodynamic torques. The adhesive torques were derived from surface interactions accessed by the extended DLVO theory. Calculation results showed that the adhesive torque of a particle located in the calculated primary minimum was slightly larger than the hydrodynamic torque, resulting in particle deposition. However, experimental data clearly indicated that detachment occurred. This could only be explained by the presence of additional hydration forces, leading to a larger separation which became relevant at high ionic strengths. By including hydration into our theoretical framework, experiment and theory were in very good agreement under all different ionic strength conditions. The findings allow a basic understanding of surface interactions between nanoparticles and membranes in micro- and ultra-filtration applications for drinking water production, wastewater treatment and particle free water production in industries.

An experimental study of ultrafiltration for sub-10 nm quantum dots and sub-150 nm nanoparticles through PTFE membrane and Nuclepore filters

Journal of Membrane Science

Ultrafiltration techniques (pore size of membrane below 100 nm) are widely used in chemical engineering, semiconductor, pharmaceutical, food and beverage industries. However, for small particles, which are more and more attracting interests, the pore size often does not correlate well with sieving characteristics of the ultra-membranes. This may cause serious issues during modeling and prediction of retention efficiencies. Herein, a series of liquid filtration experiments with unfavorable conditions were performed. PTFE membranes (50, 100 nm) and Nuclepore filters (50, 400 nm) were challenged with 1.7 nm manganese doped ZnS and 6.6 nm ZnO quantum dots (QDs), 12.4, 34.4 and 50 nm Au and 150 nm SiO2 nanoparticles. For larger and medium sized particles, sieving and eventually pore blockage phenomena were observed. In comparison, for small QDs, a high initial retention efficiency (>0.4) in both filters was monitored, followed by a reduced efficiency with ongoing particle loading. This high initial retention of small nanoparticles was attributed to diffusion deposition rather than to sieving since the ratio of pore size to particle size was significantly high (up to 58). Our experimental results allow a basic understanding of the deposition mechanism of small nanoparticles (diffusion vs. sieving) in different filter structures.